'82 Seca 750 Refresh Project: Now Scooby's Bike

That also is serious work in progress..

 

What are these rings in my cylinders and how do I get rid of them? They almost seem like carbon or dirt. It's raised off the surface rather than cut in like a deep scratch should be. Was it a piston ring issue? I'm gonna get these honed if I can. Maybe honing will do the trick. The cylinders are around 65.20-.25. Should be in spec

 

I think those look good. Nice pics by the way, hard to get the light in there. I wold guess those are just stains from the piston and rings sitting there for so long. I don't see any damage or issues with those cylinders.

 

Hey guys. I was putting back together my engine and I noticed the Haynes manual telling me to make sure the seal is on the middle gear drive. I don't remember taking off a seal when dismantling the engine, and if I did, it would be a large part, I doubt I would've thrown it out.

I see two shims behind one of the bearings and I'm wondering what are the shims for? They aren't pressing up against anything, they just free-float up and down the shaft. I looked up pictures and videos. Sometimes I find the middle gear with a seal and sometimes the middle gear doesn't have a seal. I can't remember exactly hat it looked like since I dismantled the engine during the summer. I lost all pre-dismantle pictures when my phone broke. So, I'm in the dark. What's, the deal, am I going crazy here or does the XJ750 Seca not have a seal and just these two shims?

 

Have a look at this exploded view. Part 9 is a thrust shim and 19 is for the helical gear back lash clearance. There is an oil seal number 14 on the output shaft flange.

https://www.partzilla.com/catalog/yamaha/motorcycle/1983/xj750mk/middle-drive-gear

 

Hey guys,

Anyone know the torque spec for the crankshaft bolt in the timing plate?

 

Quite daring to be undertaking an overhaul like that without having a factory manual.
Doesn't the Haynes manual have the spec?

Yamaha manual has the hex cap screw for the timing plate as 17 ft./lb.

Tony

 

Haynes doesn't always have the specs :\ unless I'm missing them somehow. I just ordered a Factory manual but it shouldn't arrive until Feb. I just checked the gear lash for my middle gear drive and am ready to torque back up the bolts but Hayne's stops at "tension up the bolts", however, they never say the torque specs. Anyone know the torque specs for these bolts?

 

18 lb./ft. with locktite.

Assembly will definitely go a lot quicker when you get the manual.

Tony

 

Hey guys, putting the clutch pressure plate back on with new springs and bolts. Torque specs are 7.2 foot lbs but... the bolts keep spinning. It shouldn't be difficult to hi the torque spec. I'm afraid any more and the bolt heads will snap off. Any tips on how to get this clutch pressure plate on successfully?

 

What range does your torque wrench have?

 

Haynes has all the specs. Some are wrong, but all of the torque values are correct.

 

+1.
If you are within 20% of either end of the range of the torque wrench it will not give a reliable reading,

 

This is the one I have and I have not used it yet.

https://www.drapertools.com/product/72623/1-4-3-8inch-Sq-Dr-Push-Through-Torque-Wrench-(5-35NM)

 

Got the torque wrench for £10 off eBay so at that price it was worth it if accurate enough.

 

Hey guys,

I have this Tekton 3/8 10-80 ft lb wrench:

https://www.amazon.com/gp/product/B00FMPKAD0/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

Although, the torque value for the bolts is 7.2, I've torqued up the other bolts on the engine with this wrench at 7.2 without an issue. I heard using a 1/4 might be best.

How risky would it be to guess the torque I put on the bolts? I've heard of people riding a bike with 4/5 clutch bolts to a shop. Might be my last resort in case I snap a clutch bolt off like a clown.

 

I would not guess the torque, on my machine and the range of your wrench is above the factory torque for the clutch bolts. You don't want to damage your clutch hub.

 

You're right. I'll just take it to a shop. Last thing I wanna do this far into the build is F something up

 

Buy the apporporiate torque wrench. It'll cost you less than a trip to any shop, and you'll know the job was actually one right.

 

i've found 7.2 is about as tight as i can make it with a screwdriver type handle with my left hand, i'm right handed
that's quick and dirty, don't use it for anything important